Granular alkali metal nitrilotriacetate and processes for producing same

ABSTRACT

CAKING-RESISTANT GRANULAR ALKALI METAL NITRILOTRIACETATE PRODUCTS ARE PREPARED BY FORMING A REACTION MIXTURE OF NITRILOTRIACETIC ACID AND ALKALI METAL CARBONATE AND WATER; THE MOLAR RATIO OF NITRILOTRIACETIC ACID TO THE ALKALI METAL CONTENT OF SAID CARBONATE BEING FROM ABOUT 1:2 TO ABOUT 1:20, SAID WATER COMPRISING FROM ABOUT 5% TO ABOUT 35% BY WEIGHT BASED UPON THE WEIGHT OF THE TOTAL REACTION MEDIUM AND DRYING THE RESULTING MIXTURE TO OBTAIN A DETERGENT ADDITIVE CONTAINING DIALKYLI METAL NITRILOTRIACETATE AND HAVING A BULK DENSITY OF FROM ABOUT 0.4 TO ABOUT 0.8 G./CC. AND HAVING ABOUT 60% OF ITS PARTICLES SMALLER THAN THE OPENINGS IN A U.S. STANDARD 10 MESH SCREEN AND ABOUT 60% LARGER THAN THE OPENINGS IN A U.S. STANDARD 60 MESH SCREEN AND LESS THAN ABOUT 8% BY WEIGHT OF WATER.

United States Patent 01 lice 3,684,744 Patented Aug. 15, 1972 U.S. Cl.252-546 4 Claims ABSTRACT OF THE DISCLOSURE Caking-resistant granularalkali metal nitrilotriacetate products are prepared by forming areaction mixture of nitrilotriaoetic acid and alkali metal carbonate andwater; the molar ratio of nitrilotriacetic acid to the alkali metalcontent of said carbonate being from about 1:2 to about '1 :20, saidwater comprising from about 5% to about 35% by weight based upon theweight of the total reaction medium and drying the resulting mixture toobtain a detergent additive containing dialkyli metal nitrilotriacetateand having a bulk density of from about 0.4 to about 0.8 g./cc. andhaving about 60% of its particles smaller than the openings in a U.S.Standard mesh screen and about 60% larger than the openings in a U.S.Standard 60 mesh screen and less than about 8% by weight of water.

This invention is a division of U.S. patent application, Ser. No.709,875, filed Mar. 4, 1968, issued Dec. 21, 1971 as U.S. Pat. No.3,629,329 and relates to granular caking-resistant products suitable fordry-blending with other detergent ingredients. More particularly, itrelates to a dry, free flowing product containing dialkyli metalnitrilotriacetate and processes for producing same.

The water-soluble salts of nitrilotriacetic acid are desirable detergentadditives. Some problems exist with the incorporation of these materialsinto detergents. For example, essentially all of the comemrcialproduction of nitrilotriacetic acid salts is by the alkaline hydrolysisof nitrilotriaminonitrile to yield trisodium or tripotassiumnitrilotn'acetate. Trisodium or tripotassium nitrilotriacetate ishygroscopic and when it is incorporated into detergent formulations, thedetergents tend to cake. The problem with caking is so acute thatmoisture barriers such as wax coatings, liners of aluminum foil, plasticand the like are used in detergent cartons to prevent caking duringstorage. While the use of such barriers in the detergent carton iseffective to prevent caking during storage, after cartons are open, thecontents can be subjected to relatively high humidity conditions,causing the detergent formulation to cake unless it is used relativelysoon after opening. It is believed, therefore, that a caking-resistantproduct which is suitable for dry blending with other detergentingredients to form a detergent formulation which is equivalent totrisodium nitrilotriacetate as a detergent builder would be anadvancement in the art. Furthermore, it is often preferred to use thedisodium, dipotassium, or mixtures of these salts in a detergentformulation to improve the detergent functional properties since thesesalts are less alkaline than the trisodium salts.

In accordance with this invention it has been discovered that acaking-resistant granular product containing dialkali metalnitrilotriacetate having a bulk density of from about 0.4 g./cc. toabout 0.8 g./cc. and having greater than about 60% of its particlessmaller than the openings in a U.S. Standard 10 mesh screen and largerthan the openings in a U.S. Standard 60 mesh screen and containing lessthan about 8% by weight of water has the desirable caking-resistantproperties, and detergent building efiiciency, and can be dry-blendedwith other detergent ingredients to form highly desirable detergentformulations that do not cake even under high humidity conditions.

The term caking resistant as used herein means that the compositionshows no appreciable tendency to cake even when subjected to pressureand stored under relatively high temperatures and high humidityconditions. For example, 50 gram samples after being placed in acylindrical container and subjected to a pressure of 5 lbs/square inchat the top surface of the sample for 48 hours and at a relativelyhumidity of and at a temperature of F. with no evidence of caking thatis upon screening with conventional screening techniques the particlesize distribution is approximately the same as before the material wassubjected to the foregoing conditioners of pressure and temperature.

The foregoing desirable detergent additive is produced by forming (1) arelatively uniform reaction mixture comprising (a) nitrilotriaceticacid, (b) alkali metal carbonate and (0) water; said reaction mixturehaving a molar ratio of nitrilotriacetic acid to the alkali metal fromat least 1:2 to about 1:20, said water being from about 5% to about 35%by weight of said reaction mixture and (2) drying the reaction mass toproduce a product containing less than about 8% water.

From about 5% to about 35% by weight of water in the reaction mixture isnecessary to produce a granular material and for good conversion of theacid. Additionally, a slurry is formed when more than 35% water is usedand excessive amounts of material having higher water solubles, andparticles smaller than the openings in a 60 mesh U.S. Standard screenare produced at lower water levels than about 5%. The preferred range ofwater level is from about 10% to about 22.5% by weight of the reactionmixture depending on the type of carbonate.

In the process of this invention order of addition is relativelyunimportant; however, it is generally preferred to form a mixture of theacid and the alkali metal carbonate and then add the water. If desired,however, the 'alkali metal salts can be mixed with water to form aconcentrated mixture and this mixture added to the nitrilotriaceticacid. Similarly, the acid and water can be mixed together and added tothe alkali metal carbonate. It is essential that the ratio ofnitrilotriacetic acid to the alkali metal in the reaction medium is atleast 1:2 on a molar equivalent basis in order to convert the acid toits dialkali metal salt since nitrilotriacetic acid is water-sinsoluble;there must be suflicient alkali metal present to form the dialkali metalsalt.

Although any alkali metal carbonate can be used such as the sodium,potassium and lithium carbonates, in most instances, sodium andpotassium carbonates are preferred. Both the monoalkali metal carbonatesand the dialkali metal carbonates can be used as long as the molar ratioof the nitrilotriacetic acid to the alkali metal is maintained withinthe ranges specified above.

The molar ratio of nitrilotriacetic acid (NTA) to alkali metal (M) inthe reaction mixture can be from 1:2 to about 1:20 and a suitableproduct is produced. Use of a larger excess of alkali metal that isabove a NTA to M molar ratio greater than about 1:20 results in highlevels of alkali metal carbonate, thus reducing the met-a1 sequestrationcapacity. Although in theory if the NTA:M molar ratio exceeds 1:3, thatis from about 123.1 to 1:20, it would be expected that thenitrilotriacetic acid would be converted to trialkali metalnitrilotriacetate (M NTA); however, formation of the trialkali metalsalt does not occur to an appreciable extent. Molar ratios of NTA:M offrom about 1:25 to about 1:5 in the reaction medium are preferred foroptimum properties of particle size, sequestration rate and density.

In theory the following reactions can occur in the process of thisinvention, wherein M is an alkali metal:

Therefore, under some conditions, it is possible to produce a productcontaining only the disodium nitrilotriacetate, however, in mostinstances, it is preferred that an excess of theory of the alkali metalcarbonate be used to insure conversion of all of the nitrilotriaceticacid. Therefore, the preferred product will contain a molar ratio ofdisodium nitrilotriacetate to alkali metal carbonate of from 1:0.25 toabout 1:15. Particularly preferred are products containing from about 5%to about 30% alkali metal carbonate, about 5% to about 8% water and fromabout 62% to about 90% disodium nitrilotriacetate.

In most instances, under preferred conditions, a relatively high yieldof product having a particle size of smaller than 10 and larger than 100US. Standard mesh screen can be obtained. The foregoing screen sizeenables the product to be blended with conventional spray-dried oragglomerated type detergents to form a formulated dry deteregnt havinghighly desirable properties. Yields of this preferred screen size, up toabout 90%, can be obtained by simple screening and followed by reducingthe oversized material to --10 mesh. The water-solubility of theproducts of the present invention is excellent, that is, essentially nowater insoluble material is present when 10.0 grams of the product aremixed with 100.0 grams of water at 25 C. If desired, other detergentadditives can be incorporated into the reaction mixture prior to thepartial neutralization of the nitrilotriacetic acid. For example, thesodium salts of l-hydroxy ethylidene 1,1-diphosphonic acid can be addedto yield a formulated builder material which is reported to havesynergistic detergent properties. It is to be noted that the bulkdensity of the product of this invention ranges from 0.4 g./ cc. to 0.8which enables the product to be dry blended with a conventional spraydried detergent or with other dry detergent ingredients such asdishwashing compounds.

The composition of this invention can be dry blended with any of theanionic, nonionic, zwitterionic or amphoteric type synthetic surfaceactive agents and mixtures of these surface active agents which havebeen previously formulated and dried by conventional deteregntmanufacturing methods.

The product can be blended with various spray dried or agglomerateddeteregnt type products containing anionic synthetic surface activeagents. Anionic synthetic surface active agents, that is non-soapdetergents, are generally described as those compounds which containhydrophilic and lyophilic groups in their molecular structure and ionizein an aqueous medium to give anions containing both the lyophilic groupand hydrophilic group. Any of these compounds or mixtures can be used.The alkyl aryl sulfonates, the alkane sulfates and sulfated oxyethylatedalkyl phenols are illustrative of the anionic type of surface activecompounds.

The alkyl aryl sulfonates are a class of synthetic anionic surfaceactive agents and can be represented by the formula:

where R is hydrogen or a straight or branched chain hydrocarbon group offrom 1 to 4 carbon atoms; R is a straight or branched chain hydrocarbonradical having from about 1 to about 24 carbon atoms, at least one Rhaving at least 8 carbon atoms; n is from 1 to 3; n is from 1 to 2; Aris a phenyl or a naphthyl radical and M is either hydrogen or an alkalimetal, such as sodium, potassium and the like; ammonium, or an organicamine such as ethanol amine, diethanol amine, triethanol amine andhexylamine and the like. R can be, for example, methyl, ethyl, ropyl,isopropyl, butyl, isobutyl and the like. R can be, for example, methyl,ethyl, hexyl, octyl, tertoctyl, iso-octyl, nonyl, decyl, dodecyl,octadecyl and the like.

Compounds illustrative of the alkyl aryl sulfonates include sodiumdodecylbenzene sulfonate, sodium decylbenzene sulfonate, ammonium methyldodecylbenzene sulfonate, ammonium dodecylbenzene sulfonate, sodiumoctadecylbenzene sulfonate, sodium nonylbenzene sulfonate, sodiumdodecylnaphthalene sulfonate, sodium heptadecylbenzene sulfonate,potassium eicosyl naphthalene sulfonate, ethylamine undecylnaphthalenesulfonate and sodium docosylnaphthalene sulfonate.

The alkyl sulfates are a class of synthetic anionic surface activeagents and can be represented by the formula RSO M, wherein M is eitherhydrogen, an alkali metal such as sodium, potassium and the like,ammonium or an organic amine, such as ethanolamine, diethanolamine,triethanolamine, ethylenediamine and diethylenetriamine, and the like;and R is a straight or branched chain saturated hydrocarbon radical,such as octyl, decyl, dodecyl, tetradecyl and hexadecyl, as well as themixed alkyl radicals derived from fatty oils, such as coconut oil,tallow, cottonseed oil and fish oil. R usually has from 8 to 18 carbonatoms.

Compounds illustrative of alkyl sulfate class of anionic surface activeagents include sodium octadecyl sulfate, sodium hexadecyl sulfate,sodium dodecyl sulfate, sodium nonyl sulfate, ammonium decyl sulfate,potassium tetradecyl sulfate, diethanolamino octyl sulfate,triethanolamine octadecyl sulfate and ammonium nonyl sulfate.

The sulfated oxyethylated alkylphenols are a class of synthetic anionicsurface active agents represented by the general formula where R is astraight or branched chain saturated hydrocarbon group having from about8 to about 18 carbon atoms, such as a straight or branched group, suchas octyl, nonyl, decyl, dodecyl and the like; A is either oxygen,sulfur, a carbonamide group, thiocarbonamide group, a carboxylic groupor thiocarboxylic ester group, x is an integer from 3 to 8 and M iseither hydrogen, or an alkali metal such as sodium, potassium and thelike, or ammonium, or an organic amine, such as ethanolamine,diethanolamine, triethanolamine, ethylene diamine and the like.

Compounds illustrative of the sulfated oxyethylated alkyl phenol classof anionic surface active agents include ammonium nonylphenoxytetraethyleneoxy sulfate, sodium dodecylphenoxy triethyleneoxy sulfate,ehtanolamine decylphenoxy tetraethyleneoxy sulfate and potassiumoctylphenoxy triethyleneoxy sulfate.

Noniom'c surface active compounds can be broadly described as compoundswhich do not ionize but acquire hydrophilic characteristics from anoxygenated side chain such as polyoxyethylene and the lyophilic part ofthe molecule may come from fatty acids, phenol, alcohols, amides oramines. The compounds are usually made by reacting an alkylene oxidesuch as ethylene oxide, butylene oxide, propylene oxide and the likewith fatty acids, a straight or branched chain alcohol, phenols,thiophenols, amides and amines to form polyoxyalkylene glycol ethers andesters, polyoxyalkylene alkyl phenol and polyoxyalkylene thiophenols,and polyoxyalkylene amides and the like. It is generally preferred toreact from about 3 to about 30 moles of alkylene oxide per mole of thefatty acids, alcohols, phenols, thiophenols, amides or amines.Additionally, the long chain tertiary amine oxides and the long chainphosphine oxides and the dialkyl sulfoxides can be used.

Illustrative of these synthetic nonionic surface active agents are theproducts obtained from the reaction of alkylene oxide with an aliphaticalcohol having from 8 to 18 carbon atoms, such as octyl, nonyl, decyl,octadecyl, dodecyl, tetradecyl and the like; with an alkyl phenol inwhich the alkyl group contains between 4 and 20 carbon atoms, such asbutyl, dibutyl, amyl, octyl, dodecyl, tetradecyl and the like; and withan alkyl amine in which the alkyl group contains between 1 to 8 carbonatoms.

Compounds illustrative of synthetic nonionic surface active agentsinclude the products obtained from condensing ethylene oxide orpropylene oxide with the following: propylene glycol, ethylene diamine,diethylene glycol, dodecyl phenol, nonyl phenol, tetradecyl alcohol,N-octadecyl diethanolamide, and N-dodecyl monoethanolamide.

Lo'ng chain tertiary amine oxides corresponding to the following generalformula, R R R N O, wherein R is an' alkyl radical of from about 8 to 18carbon atoms, and R and R are each methyl or ethyl radicals. The arrowin the formula is a conventional representation of a semipolar bond.Examples of amine oxides suitable for use in this invention includedimethyldodecylamine oxide, dimethyloctylamine oxide, dimethyldecylamineoxide, di-

'methyltetradecylamine oxide, and dimethylhexadecylamine oxide.

Long chain tertiary phosphine oxides corresponding to the followingformula RR'R"P O, wherein R is an alkyl, alkenyl or monohydroxyalkylradical ranging from 10 to 18 carbon atoms in chain length and R and R"are each alkyl or monohydroxyalkyl groups containing from 1 to 3 carbonatoms. The arrow in the formula is a conventional representation of asemi-polar bond. Example of suitable phosphine oxides are:

dimethyldodecylphosphine oxide, dimethyltetradecylphosphine oxide,ethylmethyltetradecylphosphine oxide, cetyldimethylphosphine oxide,dimethylstearylphosphine oxide, cetylethylpropylphosphine oxide,diethyldodecylphosphine oxide, diethyltetradecylphosphine oxide,bis(hydroxymethyl) dodecylphosphine oxide, bis(Z-hydroxyethyl)dodecylphosphine oxide, Z-hydroxypropylmethyltetradecylphosphine oxide,dimethyloleylphosphine oxide, and dimethyl-Z-hydroxydodecylphosphineoxide.

Dialkyl sulfoxides corresponding to the following formula, RR'S- O,wherein R is an alkyl, alkenyl, betaor gamma-monohydroxyalkyl radical oran alkyl or betaor gamma-monohydroxyalkyl radical containing one or twoother oxygen atoms in the chain, the R groups ranging from 10 to 18carbon atoms in chain length, and wherein R is methyl or ethyl. Examplesof suitable sulfoxide compounds are:

dodecylmethyl sulfoxide tetradecyl methyl sulfoxide 3-hydroxytridecylmethyl sulfoxide Z-hydroxydodecyl methyl sulfoxide3-hydroxy-4-decoxylbutyl methyl sulfoxide 3-hydroxy-4-dodecoxybutylmethyl sulfoxide 2-hydroxy-3-decoxypropyl methyl sulfoxide2-hydroxy-3-dodecoxypropyl methyl sulfoxide dodecyl ethyl sulfoxide2-hydroxydodecyl ethyl sulfoxide The 3-hydroxy-4-decoxybutyl methylsulfoxide has been found to be an especially effective detergentsurfactant.

where M is either hydrogen, an alkali metal, such as sodium, potassiumand the like or ammonium, n is an integer from 1 to 5, R is an alkylradical with from 8 to 18 carbon atoms, and R is a member selected fromthe group consisting of hydrogen, alkyl, aryl or alicyclic radicals.

For example, the C-aliphatic substituted, N-aliphatic substituted, amidoalkyl sulfonates are illustrative of the amido alkane sulfonates.Compounds illustrative of these include: sodium C-pentadecyl, N-methylamido ethyl sulfonate; sodium C-tridecyl, N-methyl amido ethylsulfonate; ammonium C-decyl, N-dodecyl amido pentyl sulfonate; potassiumC-hexadecyl, N-propyl amido propyl sulfonate; and potassium C-tridecylN-hexyl amido methyl sulfonate.

In addition the C-aliphatic substituted, N-aryl substituted, amido alkylsulfonates are illustrative of the amido alkane sulfonates. Compoundsillustrative of these include: sodium C-dodecyl N-benzene amido methyl.sulfonate; potassium C-octyl N-naphthalene amido propyl sulfonate;sodium C-hexadecyl N-benzene amido pentyl sulfonate and ammoniumC-tetradecyl N-naphthalene amido methyl sulfonate.

Also the C-aliphatic substituted, N-cycloalkyl substituted, amino alkylsulfonates are illustrative of the amido alkane sulfonates. Compoundsillustrative of these include: sodium C-dodecyl, N-cyclopropyl amidomethyl sulfonate; potassium C-tetradecyl, N-cyclohexyl amido ethylsulfonate; ammonium C-decyl, 'N-cyclopropyl amido butyl sulfonate andsodium C-octyl, N-cyclohexyl amido methyl sulfonate and the like.

Zwitterionic synthetic detergents can be broadly described asderivatives of aliphatic quaternary ammonium compounds in which thealiphatic radical may be straight chain or branched and wherein one ofthe aliphatic substituents contains from about 8 to 18 carbon atoms andone contains an anionic water solubilizing group. Examples of compoundsfalling within this definition are 3-(N, N-dimethyl-N-hexadecylammonio)propane 1 sulfonate and 3-(N,N-dimethyl-N-hexadecylammonio)2hydroxypropane-l-sulfonate which are especially preferred for theirexcellent cool water detergency characteristics.

The anionic, nonionic, ampholytic and Zwitterionic detergent surfactantsmentioned above can be used singly or in combination in the practice ofthe present invention and will be used in weight ratios of surfaceactive agent to the product of this invention of from about 1:10 to 10:1with weight ratios of from 1:5 to 5:1 being preferred. The aboveexamples are merely specific illustrations of the numerous detergentswhich can find application within the scope of this invention.

Other illustrative surface active agents can be found in Schwartz andPerry, Interscience Publishers, New York, Surface Active Agents, vol. I(1949) and vol. II (1958), which are incorporated herein by reference.

In addition to the foregoing surface active agents, in most instancesother detergent additives will be used, such as the well-known phosphatedetergent builders such as sodium tripolyphosphate, tetrasodiumpyrophosphate, sodium and potassium sulfates and carbonates, sodiumsilicate, optical brighteners, corrosion inhibitors, anti-redepositionagents, dyes and pigments as well as the organic sequestering agentsdisclosed in US. Pat. 3,368,978. In most instances, the foregoingdetergent additives will be used in amounts of from 10% to of the totaldetergent formulation. Generally a formulated detergent base containingmixtures of the foregoing detergent additives and surface active agentswill be prepared in a conventional manner such as by the conventionalspray drying technique or by the preparation of a detergent baseutilizing the reaction of sodium hydroxide and sodium trimetaphosphateto produce a material containing the normal detergent additives, asurface active agent and sodium tripolyphosphate hexahydrate as isdisclosed in U.S. patent application Ser. No. 460,205, now U.S. Pat. No.3,390,- 093.

The foregoing detergent bases will be blended with the composition ofthis invention to yield a detergent composition having from about 2 toabout 55% by weight of nitrilotriacetates calculated on the basis ofnitrilotriacetic acid. Preferred ranges are usually from about 5 toabout 40% by weight calculated as nitrilotriacetic acid.

To further illustrate this invention, the following nonlimiting examplesare presented. All parts, proportions and percentages are by weightunless otherwise indicated.

EXAMPLE 1 About 1880 parts by weight of nitrilotriacetic acid and about1565 parts of sodium carbonate are charged into a ribon blender. Afterthe mixture is relatively uniformly mixed, about 600 parts of water areadded through a nozzle to give a relatively uniform water distributionover the bed of the nitrilotriacetic acid soda ash mixture. Afterblending for about 15 minutes, the material is dried in a forced-draftoven at 150 F. The dried material was screened through a mesh and theoversize was coarsely milled and rescreened. A sample of the materialhas particles larger than the openings in a U.S. Standard 60 meshscreen. The bulk density of a sample of the material measured 0.4 g./cc.Utilizing essentially the same procedure only adding 150 parts of water,the material is insufficiently agglomerated and not all of thenitrilotriacetic acid converted to the water-soluble salt. Whenessentially the same procedure is followed with the exception that 800parts of water are added, essentially the same results are achieved aswhen 600 parts of water were added with a slight increase in the desiredparticle size range. When 1,000 parts of water are added, essentiallyall of the product is recovered in the -l0 to +60 mesh screen size.Adding larger amounts such as 1200 parts of water increases the densityof the resulting product to about 0.6 which is desired for incorporationin some denser detergent formulation such as dishwashing compositions.At levels above 1200 parts the product is too wet to handle; thus it isconcluded that from about 5% to about 35% of water is required toachieve the product of this invention with from about to about beingparticularly preferred for this formulation.

EXAMPLE 2 About 150 parts of ultramarine blue is incorporated togetherwith materials prepared in the same manner as described in Example 1.The 0.4 g./cc. density'blue beads at a level of 510% are blendedtogether with a white, traditionally prepared spray-dried detergentgranule. The blue beads do not separate from the spray-dried detergentgranules and have low tendency to cake, and help to control the metalions by forming soluble metal chelates to prevent the precipitation ofanionic surface active agents.

EXAMPLE 3 Three hundred and five parts by weight of nitrilotriaceticacid are mixed with 144 parts light soda ash, 149 parts potassiumcarbonate, 100 parts trisodium salt 1- hydroxyl ethylidenediphosphonate, 78 parts .pentasodium tripolyphosphate, and 2 parts alkylpolyoxyethylene ether (a nonionic surfactant) in a twin shell blender.About 670 parts of a 37.5% sodium silicate with an SiO to Na O weightratio of 1.80 (containing about 420 partsof water, or 29% of the totalchange) is sprayed through a disk-type sprayer located near the centerof the blender at a uniform rate over a period of half hour. The blenderhas a value for venting the CO from the reaction of the carbonates andnitrilotriacetic acid to form the dialkalimetal salts. The sized productcontains less than 10% smaller than 60 mesh, and has a bulk density ofabout 0.65 grams per cubic centimeter. After drying to remove the excessmoisture, about 3 parts of a granular potassium chlorine cyanurate areblended together to give a superior automatic dishwashing compound. Whena sample is exposed to a relative humidity of at F. and to a pressure of5 lbs/square inch for a period of 24 hours, the product from the processdescribed above remains free-flowing. If the same composition isslurried so that most of the nitrilotriacetate salt is in thetri-substituted form and spray-dried, the resulting product cakes aftervexposure to 80% RH at 30 C. for 24 hours. A Wax-lined box is requiredfor the latter type of product.

What is claimed is:

1. A caking-resistant granular detergent additive consisting essentiallyof disodium nitrilotriacetate having a bulk density of from about 0.4 to0.8 g./ cc. having about 60% of its particles smaller than the openingsin a U.S. Standard 10 mesh screen and larger than the openings in a U.S.Standard 60 mesh screen, containing an alkali metal carbonate and atmost about 8% by weight of Water, the molar ratio of disodiumnitrilotriacetate to alkali metal carbonate being from 120.25 to about111.5.

2. A detergent additive according to claim 1 wherein said alkali metalcarbonate is sodium carbonate.

3. A detergent composition consisting essentially of (a) a surfactantcontaining a surface active agent selected from the group consisting ofanionic, nonionic, zwitterionic, amphoteric surface active agents andmixtures thereof, and (b) a detergent additive consisting essentially ofdialkali metal nitrilotriacetate having its particles essentiallysmaller than the openings in a U.S. Standard 10 mesh screen and largerthan the openings in a U.S. Standard 60 mesh screen, having a bulkdensity of from about 0.4 to 0.8 g./cc.; containing an alkali metalcarbonate and at most 8% water by weight, the molar ratio of disodiumnitrilotriacetate to alkali metal carbonate being from 1:0.25 to 1:1.5;said detergent composition containing from) about 2% to about 55% ofnitrilotriacetates calculated on the basis of nitrilotriacetic acid theweight ratio of said surface active agent (a) to said detergent additive(b) being from about 1:10 to 10:1.

4. A detergent composition according to claim 3 whereing said detergentadditive contains from about 5% to about 30% by weight of alkali metalcarbonate.

Pollard, Robert: Amino Acids Chelating Agents in Detergent, Soap &Chemical Specialties (September 1966), pp. 58-62, -135.

LEON D. ROSDOL, Primary Examiner D. I. ALBRECHT, Assistant Examiner I,U.S. c1. X.R. 252M180, 383, 384, 385, 527, DIGEST ll P0-105O UNITEDSTATES PATENT GFFICE (5/69) QERTTFKATE UT" QQREQTKQN Patent No.5,684,744 Dated Auggst 15, 1972 Inventor) Chung Yu Shen. and Norman EarlStahlheber It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

in Column 5, line 11, the end of formula reading "+EMRCO- =,+CO +H 6should read ---+2MHCO +CO +H2O.

Signed and sealed this 9th day of January 1973.

(SEAL) Attest:

ROBERT GOTTSCHALK Commissioner of Patents EDWARD M.FLETCHER,JR.Attesting Officer PO-1O5OV UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 5,684,744 Dated August 15, 1972 lnvmumr(s) ChungYu Shen and Norman Earl Stahlheber It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

IB Column 5, line 11, the end of formula reading'42MRCO w CO rH 6 shouldread --+2MHCO3+CO2+H2O--.

Signed and sealed this 9th day of January 1973.

(SEAL) Attest:

ROBERT GOTTSCHALK Commissioner of Patents EDWARD M.FLETCHER,JR,Attesting Officer

